The Trump administration has declared a public health emergency in the United States over the new coronavirus and has implemented quarantines and other restrictions to curb the virus' spread—as the number of confirmed cases of the virus in the United States reached 11 as of Sunday.

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Some experts have raised concerns that the virus could become a pandemic, noting the virus' rapid spread in China and other countries, and U.S. health care providers are scrambling to screen patients who might have the virus.

About the new coronavirus

Reports of the new coronavirus first surfaced in early December 2019 among people in Wuhan, China. According to the World Health Organization (WHO), the main symptoms of the virus, called 2019-nCoV, are fever and lesions in both lungs. Some patients also have reported difficulty breathing, WHO said.

Officials in China said there were 361 reported deaths linked to the virus as of Monday. One of those deaths occurred in the Philippines, while all of the others occurred in China.

As of Monday, WHO had reported at least 17,205 confirmed cases of the virus.

Officials have reported confirmed cases of the virus in more than two dozen countries, but the vast majority of confirmed cases have been in China.

In the United States, CDC has confirmed a total of 11 cases of the new coronavirus. Most of the cases are among patients who had visited China, though two of the cases involve patients who contracted the virus from their spouses who had visited China. CDC as of Sunday had confirmed six cases of the virus in California, two cases in Illinois, and one case each in Arizona, Massachusetts, and Washington.

US declares public health emergency, implements travel restrictions and unprecedented quarantines

HHS Secretary Alex Azar on Friday declared a public health emergency in the United States over the new coronavirus, though he stressed that the virus' risk to Americans remains low.

"While this virus poses a serious public health threat, the risk to the American public remains low at this time, and we are working to keep this risk low," Azar said. He continued, "We are committed to protecting the health and safety of all Americans, and this public health emergency declaration is the latest in the series of steps the Trump administration has taken to protect our country."

The declaration, which is retroactive to Jan. 27, allows state, tribal, and local health departments to request HHS' permission to temporarily reassign personnel to respond to the new coronavirus. The declaration also allows the federal government to implement certain temporary measures to combat the virus.

Under the proclamation, the Trump administration has implemented certain quarantine policies and travel restrictions. For example, the administration has ordered that, beginning at 5 p.m. Sunday, all passengers on flights to the United States who were in China's Hubei province—which is the epicenter of the new coronavirus outbreak—at any point in the past two weeks will be subject to a 14-day mandatory quarantine. CDC already has quarantined 195 Americans the federal government evacuated from China last week. The individuals will remain quarantined at March Air Reserve Base in California through the end of a 14-day period. According to CBS News, the new quarantine requirement marks the first time the federal government has instituted a mandatory quarantine order since the 1960s, when officials were trying to stop the spread of smallpox in the country.

According to the Wall Street Journal, Department of Defense officials announced that they are preparing four military bases in California, Colorado, and Texas to hold Americans who return to the United States and must be quarantined because of the virus. Officials said the bases will be able to house as many as 1,000 quarantined individuals through the end of February.

DOD in a statement said, "Under [HHS'] request, DOD will only provide housing support, while HHS will be responsible for all care, transportation, and security of the evacuees. DOD personnel will not be directly in contact with the evacuees and evacuees will not have access to any base location other than their assigned housing."

Officials said, if any of the quarantined individuals are confirmed to have the new coronavirus, HHS personnel would transfer the patients to local civilian hospitals. Officials said the bases as of Sunday had not received any patients.

In addition, the Trump administration has ordered that any American who has visited any part of mainland China outside of the Hubei province to be screened at one of seven airports that are currently screening travelers for symptoms of the virus. Those airports are located in Atlanta, Chicago, Honolulu, Los Angeles, New York, San Francisco, and Seattle.

Officials will allow individuals who have visited any part of mainland China outside of the Hubei province and who have no detected symptoms of the virus to return to their homes. However, such individuals must stay isolated at home and will be monitored by local health officials.

The U.S. Coast Guard also will prohibit ships from entering U.S. ports if they had traveled to China within the past two weeks or had any passengers that had been to China within the past two weeks. However, the Coast Guard will allow cargo ships that have been to China within the past two weeks to enter U.S. ports as long as none of their passengers are showing symptoms of the virus.

Further, Azar said President Trump has signed a presidential proclamation that "temporarily suspend[s] the entry into the United States of foreign nationals who pose a risk of transmitting the 2019 novel coronavirus." Azar said, "Foreign nationals other than immediate family of U.S. citizens and permanent residents who have traveled in China in the last 14 days will be denied entry into United States."

Experts worry outbreak could become a pandemic

U.S. officials' heightened response comes as experts raise concerns that the new coronavirus could become a pandemic. According to Business Insider, cases of the new coronavirus in less than one month have outpaced the number of cases seen in the early 2000s SARS outbreak, which was considered as "'the first pandemic of the 21st century.'"

Nancy Messonnier, director of CDC's National Center for Immunization and Respiratory Diseases, on Friday said, "We are preparing as if this were the next pandemic, but we are hopeful still that this is not and will not be the case."

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said the United States is forcefully responding to the new coronavirus because "there are a lot of unknowns" about the virus. Fauci noted that "[t]he number of cases" of the new virus "has steeply inclined each and every day," and evidence has shown the virus can be transmitted by patients who aren't showing symptoms of infection. He said, "It's very, very transmissible, and it almost certainly is going to be a pandemic."

Former CDC Director Thomas Frieden, who now heads the nonprofit Resolve to Save Lives, said it's "increasingly unlikely that the virus can be contained," and "is therefore likely that it will spread, as flu and other organisms do, but we still don’t know how far, wide, or deadly it will be."

US hospitals should 'dust off pandemic plans'

Experts also have raised concerns that spread of the new coronavirus in the United States could strain health care providers as they also grapple with an increasing number of flu cases in the country.

Dara Lieberman, director of government relations for the advocacy group Trust for America's Health, said, "Health care and emergency care is already at capacity in a lot of areas, so any strain on the system could be catastrophic, depending on what kind of outbreak we're facing."

Eric Toner, a senior scholar at the Johns Hopkins Center for Health Security, said, "Hospitals should be dusting off their pandemic plans," adding, "We don't yet know whether this will become a pandemic, but it takes time to do the education and refresher training that hospital staff are going to need."

Outbreak threatening drug supply chain, other markets

In addition to experts' concerns about the strain the new coronavirus outbreak could place on providers, experts say the outbreak also could threaten the prescription drug market—as the outbreak already is having significant effects on the global economy overall.

According to Axios, "Stocks saw the worst sell-off in months on Friday," with the Dow Jones Industrials Average dropping 603 points, or 2.1%; the S&P 500 dropping 1.7%, and the Nasdaq declining 1.5%

Several airlines also have halted or limited their services to China. And some businesses in China, including Apple and Levi Strauss & Co., have temporarily closed locations throughout China. Further, some large pharmaceutical companies have begun evacuating expatriate workers from China. The moves threaten both sales and product production that could have implications for China and countries around the world, Bloomberg reports.

FDA Commissioner Stephen Hahn on Friday said there have not yet been any reports of disruption or shortages in the drug supply chain as a result of the new coronavirus. However, he said the agency is planning for "what could potentially be the most serious of scenarios" (McKay, Reuters, 2/2; CBS News, 2/3; Yao/Sun, Reuters, 2/2; Axios, 2/3; Miller/Edwards, NBC News, 1/31; HHS release, 1/31; Aubrey, "Shots," NPR, 1/31; Yang et al., Wall Street Journal, 2/2; Starr/Bohn, CNN, 2/1; Owermohle/Karlin-Smith, Politico, 1/31; McNeil, New York Times, 2/3; Woodward/Perper, Business Insider, 2/3; Siddons, Roll Call, 1/31; Ross Johnson, Modern Healthcare, 2/1; Daurat, Bloomberg, 1/31; Areddy, Wall Street Journal, 2/3; Brown/Rabouin, Axios, 1/31).